NUR-255 Test 1 Review Exam Questions & Answers, Rated 100%

NUR-255 Test 1 Review Exam Questions & Answers, Rated 100%,When computing a heart rate on a patient's electrocardiogram (ECG) tracing, the nurse counts 15 small blocks in an R-R interval. The rhythm is regular. Which heart rate in beats/min would the nurse document? A) 60 B) 75 C) 100 D) 150-C) 100 Rationale Because each small block on the ECG paper represents 0.04 second, 1500 of these blocks represent 1 minute. By dividing the number of small blocks (15 in this case) into 1500, the nurse can calculate the heart rate in a patient whose rhythm is regular (in this case, 100 beats/min). Heart rates of 60 beats/min, 75 beats/min, and 150 beats/min are incorrect answers. p. 887 Which phrase describes the electrical activity represented by the PR interval on an electrocardiogram (ECG)? A) The length of time it takes to depolarize the atrium B) The length of time it takes for the atria to depolarize and repolarize C) The length of time for the electrical impulse to travel from the sinoatrial (SA) node to the Purkinje fibers D) The length of time it takes for the electrical impulse to travel from the SA node to the atrioventricular (AV) node-C) The length of time for the electrical impulse to travel from the sinoatrial (SA) node to the Purkinje fibers Rationale The electrical impulse in the heart must travel from the SA node through the AV node and into the Purkinje fibers for synchronous atrial and ventricular contraction to occur. When measuring the PR interval (the time from the beginning of the P wave to the beginning of the QRS), the nurse is identifying the length of time it takes for the electrical impulse to travel from the SA node to the Purkinje fibers. The P wave represents the length of time it takes for the impulse to travel from the SA node through the atrium, causing depolarization of the atria (atrial contraction). Atrial repolarization occurs during ventricular depolarization and is hidden by the QRS complex. The length of time it takes for the electrical impulse to travel from the SA node to the AV node is the flat line between the end of the P wave and the beginning of the Q wave on the ECG and is not usually measured. p. 888 Which electrocardiogram (ECG) characteristic will be present if a patient is experiencing unifocal premature ventricular contractions (PVCs)? Select all that apply. One, some, or all responses may be correct. 1) Normal T wave 2) Normal P wave 3) PR interval that is not measurable 4) Wide and distorted QRS complex 5) PVCs that have the same shape A) 1,3,4,5 B) 2,3,4,5 C) 3,4,5 D) 1,2,3 E) All F) None-A) 1,3,4,5 Rationale A PVC is a contraction that results from an ectopic focus in the ventricles. In other words, the QRS complex occurs prematurely. The T wave is generally normal. The PR interval is not measurable. The QRS complex is wide and distorted in shape compared with a QRS complex coming down a normal conduction pathway. PVCs that arise from the same foci appear the same in shape and are called unifocal PVCs. The P wave is rarely visible and is usually hidden in the PVC. p. 897 A patient's electrocardiogram (ECG) shows a heart rate of 150 beats/min and a normal P wave preceding each QRS complex. Which interpretation would the nurse make of these findings? A) Atrial fibrillation B) Sinus tachycardia C) Ventricular fibrillation D) Premature atrial contractions-B) Sinus tachycardia Rationale Sinus tachycardia includes a heart rate of 101 beats to 180 beats per minute. The electrocardiographic study of sinus tachycardia shows a normal P wave preceding each QRS complex with normal time and duration. In atrial fibrillation, the P waves are chaotic and fibrillatory and the QRS complex is normal. The electrocardiographic study of ventricular fibrillation elicits the absence of P waves, and the PR interval and QRS interval cannot be measured. In premature atrial contraction, there are distorted P waves in the ECG. pp. 891-892